2 Answers
2

It’s quite simple: You create a symbolic link in ~ that points to ./abcin that directory. The pathname of a symbolic link must be valid in the context of the directory it is in¹. If you indeed want to point to the file that is in your now current directory, you must use the full path.

The link must be valid if you want to use it. It can point into nothingness or to a file that does not exist. That can be a good thing, as the file might have been there before and can reappear any time, and the symbolic link will then point to it again.